Solid-liquid Phase Equilibria of Li+, Na+, Ca2+//Cl--H2O Quaternary System at 298.15 and 323.15 K

The solid-liquid phase equilibria of the Li+, Na+, Ca2+//Cl--H2O quaternary system at 298.15 and 323.15 K are studied via the isothermal solubility phase equilibrium method. The solubility data and liquid properties of density and pH are obtained. The phase diagrams of the quaternary systems, including the water free diagram, the water diagram, and the dry salt diagram, are plotted to show the phase regions, water content, and salting-in effect. NaCl occupies the largest phase region at both 298.15 and 323.15 K. One double salt LiCl<middle dot>CaCl2<middle dot>5H(2)O occurs at 298.15 K and builds up two invariant points; one incommensurate invariant point saturated by (NaCl, LiCl<middle dot>H2O, LiCl<middle dot>CaCl2<middle dot>5H(2)O) and one commensurate invariant point saturated by (NaCl, CaCl2<middle dot>4H(2)O, LiCl<middle dot>CaCl2<middle dot>5H(2)O), but at 323.15 K, no double salt forms. The salting-in effect that happened in ternary systems still occurs in the quaternary Li+, Na+, Ca2+// Cl--H2O system at both temperatures. NaCl saturated concentration increases with LiCl and CaCl2 contents and results in a very high total salt content at commensurate invariant points, e.g., they are 56.92 and 60.62% at 298.15 and 323.15 K, respectively.